a boy takes 15min to reach his school on bicycle.if the bicycle have speed of 2m/s the what is the distance between the house an
1 answer:
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Answer:
His pitching speed is 38 m/s.
Explanation:
Hi there!
Please see the attached figure for a better understanding of the problem.
The position of the ball at any time t is given by the following vector:
r = (x0 + v0 · t, y0 + 1/2 · g · t²)
Where:
r = position vector of the ball at time t.
x0 = initial horizontal position.
v0 = initial horizontal velocity.
t = time.
y0 = initial vertical position.
g = acceleration due to gravity (-9.8 m/s² considering the upward direction as positive).
Let's place the origin of the frame of reference at the throwing point so that x0 and y0 = 0.
When the ball reaches the ground, its position vector will be r1 (see figure). Using the equation of the vertical component of the position vector, we can find the time at which the ball reaches the ground. At that time, the horizontal component of the position is 30 m and the vertical component is -3.0 m (see figure):
y = y0 + 1/2 · g · t² (y0 = 0)
y = 1/2 · g · t²
-3.0 m = 1/2 · (-9.8 m/s²) · t²
-3.0 m / -4.9 m/s² = t²
t = 0.78 s
Now, knowing that at this time x = 30 m, we can find v0:
x = x0 + v0 · t (x0 = 0)
x = v0 · t
30 m = v0 · 0.78 s
v0 = 30 m / 0.78 s
v0 = 38 m/s
His pitching speed is 38 m/s.
Answer:
Counterclockwise
Explanation:
We need to calculate the clocwkise and the counterclockwise torque.
The clockwise torque is the one generated by the child sitting on the right. This torque is given by:
where
is the force exerted by the child (his weight)
d = 1.8 m is the distance from the pivot point
So, the clockwise torque is
The counterclockwise torque is the one generated by the adult pushing on the left, and it is given by
where
F = 151 N is the force applied
d = 3.0 m is the distance from the pivot
Substituting,
So, the net torque is
And since the counterclockwise momentum is greater than the clockwise one, the teeter-totter will rotate counterclockwise.